The present invention relates to binocular stereoscopic magnifying systems and to combined illumination and binocular stereoscopic magnifying systems. More particularly, the present invention relates to such systems which are worn on the head and are particularly suited for use by surgeons.
It is difficult for human eyes to observe a small object located beyond a small opening, or in or at the end of a narrow passageway. When the object is brought close enough to see it clearly, there may be problems with stereoscopic focusing through the opening or along the narrow passageway using both eyes. Use of one eye to obtain a satisfactory focus has the disadvantage of loss of depth perception. When the object is sufficiently spaced from the eyes to provide a satisfactory stereoscopic focus, visual acuity is diminished. Thus, stereoscopic focus and visual acuity are competing factors. When it is necessary or desirable to illuminate the object being viewed by projecting illumination through the opening or narrow passageway, additional problems are presented.
The aforementioned problems exist particularly in the surgical field where the surgeon must position himself sufficiently distant from the operating area to enable him to operate while being sufficiently close thereto to enable him to clearly see the operating area. This distance may place the surgeon's eyes in the range of from about 5 inches to about 30 inches, usually from about 8 inches to about 20 inches, from the operating area. In these ranges, the aforementioned problems of visual acuity and easy stereoscopic focus exist, particularly for small objects located beyond small openings or in or at the end of a narrow tube or passageway. For neurosurgeons, the problem becomes acute when operating in or through a nasal passage or auditory canal, for example. Individual surgical telemicroscopes and eye loupes worn by the surgeon are not entirely satisfactory in that it is still difficult to obtain stereoscopic vision and depth perception, particularly through small openings or in or at the end of narrow passageways. Operating room microscopes may be used. However, they are large and bulky, and are burdensome to use, move and adjust. They also restrict the surgeon's mobility and may cause eye fatigue during long periods of use. There also exists the additional problem of projecting illumination through small openings or along narrow passageways to the operating area and at the same time viewing the area. Conventional fiber optics head lamps used with eye loupes are also not satisfactory not only because of the difficulty in stereoscopically viewing the operating area as described above, but also because it is extremely difficult to maintain illumination on the operating area and a stereoscopic focus with even the slightest movement of the surgeon's head. Such eye loupes are positioned adjacent each eye of the surgeon and are consequently relatively widely spaced, with the minimum spacing being determined by the interocular distance of the particular surgeon. The optical axis of the fiber optics head lamp is located between the axes of the loupes. A wide angle of convergence is thereby formed between the widely spaced optical axes of the loupes and the surgeon must precisely position himself to locate the convergence point through the small opening or in the narrow passageway while providing a path of vision for each eye which is not blocked by the edges of the opening or sides of the passageway. Slight movement of the surgeon's head may result in the path of vision to one of the eyes being blocked by the edges of the opening or sides of the passageway. This makes it extremely difficult to both illuminate and view with both eyes a small object or operating area located beyond a small opening or in or at the end of a narrow passageway using known systems of the type described.
The invention disclosed herein overcomes the aforementioned drawbacks and provides improved binocular stereoscopic magnifying apparatus and combined binocular stereoscopic magnifying and illuminating apparatus.